Re: [PATCH] of/kexec: Omit kaslr-seed when kexecing with nokaslr

[Song Shuai]

在 2023/9/8 22:58, Rob Herring 写道:
> On Fri, Sep 8, 2023 at 5:45 AM Song Shuai <songshuaishuai@xxxxxxxxxxx> wrote:
> > The chosen node always adds the kaslr-seed property which is needless
> > for the kernels kexeced with the cmdline contained "nokaslr".
> >
> > So omit the kaslr-seed when kexecing with nokaslr.
>
> The kexec'ed kernel can ignore bootargs with CONFIG_CMDLINE_FORCE. So
> you don't know if kaslr-seed will be used or not.
You are correct. In addition, unlike the EFI Stub, Kexec is unable to
determine whether the kexec'ed kernel supports RANDOMIZE_BASE,
hence it is appropriate to emit the kaslr-seed unconditionally like
those out-of-linux bootloaders.

Apologies for bothering you with this incorrect patch.

> > Signed-off-by: Song Shuai <songshuaishuai@xxxxxxxxxxx>
> > ---
> >   drivers/of/kexec.c | 15 ++++++++++++---
> >   1 file changed, 12 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
> > index f26d2ba8a371..c0d53b10cb70 100644
> > --- a/drivers/of/kexec.c
> > +++ b/drivers/of/kexec.c
> > @@ -19,6 +19,7 @@
> >   #include <linux/random.h>
> >   #include <linux/slab.h>
> >   #include <linux/types.h>
> > +#include <linux/string.h>
> >
> >   #define RNG_SEED_SIZE          128
> >
> > @@ -263,6 +264,14 @@ static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
> >   }
> >   #endif /* CONFIG_IMA_KEXEC */
> >
> > +static bool is_nokaslr_cmdline(const char *cmdline)
> > +{
> > +       char *str;
> > +
> > +       str = strstr(cmdline, "nokaslr");
> > +       return str == cmdline || (str > cmdline && *(str - 1) == ' ');
>
> Yet another copy of the same code. That's a clue to refactor into a
> common function.
>
> Rob

--
Thanks
Song Shuai